Telephone-exchange



No. 748,980. PATENTED JAN. 5, 1904.

N. E. NORSTROM. TELEPHONE EXCHANGE.

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PATENTED JAN.5, 1904.

N. E.' NORSTROM. TELEPHONE EXCHANGE.

APPLICATION FILED MAR. 16. 1901.

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UNITED STATES Patented January 5, 1904.

PATENT OFFICE.

NILS EMEL NORSTROM, OF CHICAGO, ILLINOIS, ASSIGNOR OF TWO-THIRDS TO JOHN ANDERSON, OF SALINA, KANSAS, AND M. E. RICHARDSON, OF

STERLING, KANSAS.

TELEPHONE-EXCHANGE.

SPECIFICATION-forming part of Letters Patent No. 748,980, dated January 5, 1904. Application filed March 16, 1901. Serial No. 61,462. (No model.)

T at whom it may concern:

Be it known that I, NILs E EL NORSTROM, a citizen of the United Statesof America, and a resident of Chicago, county of Cook, and

State of Illinois, have invented certain new and useful Improvements in Telephone-Exchanges, of which the following is a specification.

My invention relates to telephoneexchanges, and more particularly to those forms of exchanges in which a series of telephone stations are connected to the same party-line.

The object of my-invention is to makecertain improvements in the apparatus at the r 5 local stations, one feature of whichis the arrangement of relay-magnets in combination with a magneto-generator and the connections to and from both.

Another feature is such an arrangement of electrical connections that when two stations are in telephonic connection a subscriber at some other station cannot send an impulse to the central office until the two subscribers who are talking have had their apparatus returned to normal positions.

In the said drawings, Figure 1 is a diagram illustrating the principal apparatus at a cen tral oftice from which two wires 50 and 100 extend. Also in Fig. 1 there is a diagram of a telephone-station connected to the lines 50 and 100. In Fig. 2 are two similar stations also connected to the lines 50 and 100. Fig. 3 is a plan of the switching mechanism. Fig. 4 is a section on line 4 4 of Fig. 3, the ratchet Fig. 5 is an elevati'on showing the manner of connecting the relay to the permanent magnets of the generator; and Fig. 6 is an elevation, being a view in the direction of the arrow 6 of Fig. 5.

40 In the said drawings the apparatus at the cemral office, so far as herein shown, consists of a receiver R, transmitter T, the usual induction-coil and battery, a drop D, and keys for making electrical connections, as will be 5 hereinafter described. At each local station there is also a receiver R, a transmitter T, a generator G, a battery Y, induction-coil K, bell-ringer Q, a switch M, provided with a pointer or contact-maker P, a magnet A for moving the pointer, a magnet B for releasing it, and two relays O and E for controlling the operations of the magnets A and B. The relays O and E are attached to the magnetogenerator G and so arranged that the magnets of said generator will give opposite polarities to the said relays O and E. Opposite the poles of the relays O and E there is an armature O, which may be attracted by either relay, closing and opening contact connections, as will be apparent by examination of the drawings and as will appear in the subseqent description of the operation. In the path of each pointer or contact-maker P there is a contact-point J, which is located at the normal position of the said pointer P. Also in the path of the pointer P there is a contact-point J, and the two contact-points J and J are connected by a wire 8 to the partyline wire 50. The contact-points J and J are different distances from each other at the diiferent stations. Thus in station No. 1 there is one intervening space or blank contact-point between J and J, at station No. 2 there are two such blank spaces between J and J, at station N0. 3 there are three blank spaces, and at other stations similarly numbered there would be a similar number of blank spaces between J and J. The apparatus at each station is connected to and controlled froin the central office, so that when the operator at the central office moves one of the contact-makers P she also moves every other one unless one of them be stopped, so

'as to prevent movement in the manner that will be described hereinafter.

The switching mechanism consists of a ratchet M, which is mounted upon a post M supported in a base V. Pivoted on the post M is an armature A, which is operated upon by the magnet A and which is provided with a pawl A adapted to engage the ratchet-wheel M. On the armature B of the magnet Bis a holding-pawl B so arranged with respect to the moving-pawl A that when the magnet B operates to release the holding-pawl B? the said holding-pawl will strike and lift the pawl A tb us completely releasing the ratchetwheel M. When this release occurs after the wheel has been moved by the action of magnet A, the spring M on the post M returns the ratchet-wheel M to its normal position.

The polarization of the relays C and E is maintained by attaching them direct to opposite ends of the permanent magnets of the generator G, as shown in Fig. 5. Supported adjacent to the relays C and E is a plate W of insulating material, and on this plate is supported the armature O. This armature is in a single piece and is held in a mid-position by springs 86 and 89, which are normally in electrical connection with contact-points 85 and 88. When the relay E is energized, the armature O is moved into contact with a suitable spring or contact-point47, at the same time breaking the connection between 85 and 86. \Vhen the relay 0 is energized, the armature O is moved to contact with 55 and breaks the connection between 88 and 89.

Assuming that the subscriber at telephonestation No. 1 wishes to talk to the subscriber at telephone-station No. 3, then the operation would be as follows: Without removing his receiver the subscriber at telephone-station No. 1 turns the crank of his generator G,when acurrent flows as follows: G, 5, 6, 7, M, P, J, 8, 50, 16, 17,D, 18, 19, D, 20, 21, 22, 23,36, 9, 100 back to line 10 of the calling-station 11, H, 12, 13, Q, 14, 15, G. This operates the drop D at the central office and indicates to the operator there that a subscriber wishes to talk. The operator then presses key into connection with contact-point 29 and the subscriber at station No. 1 removes his receiver from the hook H, when the talking-circuit between the central office and thelocal station is as follows: beginning at K of the calling-station, 24, R, 7, M, P, J, 8, to the central ofice, 26, K, 27, R, 28, 29, 30,31,100 back to 10 of station No. 1, 11, H, 32, 33, K. After informing the central oifice that he wishes to talk to the subscriber at station No. 3 he returns his receiver to the hook when the central office presses key 21 and sends a current as follows: battery X, 20, 34,35, 36, 9, 100,110 of each local station on the line E,C,37,ground at each local station toground atcentral, 38, 39, 21,X. This sends a current through the polarized relays O and E of each station, and, as the two are oppositely polarized,the current sent through them actuates only one of them-as, for example, in this case the relay E, thus closing 0 to 47. Upon the closure of G to 47 a local circuit within the station goes from battery Y, 40, 41, A, 42, 43, 44,45, 46, 47, 0, base of generator G, 48, 49, Y. This operates the magnet A, which is used to move the pointer P forward. The same operation occurs at each one of the local stations, so that upon the operator at central office closing the key 21 once, each pointer Pis moved forward one step away from the normal contact-point J. The operator repeats this arequired number of times, which in this case would be twice, to cause the contact-maker or pointer P of station No. 1 to rest upon the contact-point J. It will be apparent from the previous description that when the contact-maker P is on its connection J all of the other contactmakers at the other stations are at blank positions. Having moved the contact-maker of station No. 1 to the contact-point J, the operator at central sends a current from her generator G, 9, 100 to 10 of station No. 1, 11, H, 12, 13, Q, 14, 25, G, 48, 49, 40, 41, A, 80, 60, M, P, J, 8, 50, G. This calls the subscriber at station No. 1, who removes his receiver, whereupon the operator at central oifice again presses the key 21, so as to move the pointer P forward until the one at station No. 3 is on its contact-point J. When the subscriber at station No. 1 removes his receiver from its hook after being called, the circuit for operating his switching mechanism is broken. Consequently his pointer P remains in connection with his contact-point J, while all of theotherpointersaremoved forward. When the pointer of station No. 3 is on its contactpoint J, the central again operates her generator, calling the subscriber at station No. 3, who removes his receiver. The talkingcircuit between the two stations is then as follows: beginning at K of station No. 1, 24, R, 7, M, P, J, 8, 50 to connection 8 of station No. 3, P, J, 7, R, 24, K, 33, 32, H, 11, 10, 100, back to connection 10 of station No. 1, 11, H, 32, 33, K. When through talking, the subscriber at station No.1 rings oif, whereupon the operator at central office closes key 51, when a current fiows as follows: X, 20, 34, 51, 52, 53, 38, ground at central office to ground at each local station, 37 of each station, 0, E, 10, 100, 9, 23, 22, 21, X. This sends an impulse in an opposite direction through the relays O and E, which are connected together in series, and energizes O, attracting the armature C, so as to close it to 55. A current then flows at each station Y, 40, B, 54, 55, 0, base of generator, 48, 49, Y. This operates the release-magnet B, which releases the operating mechanism from the pointer P and permits it to fall back to its normal position in connection with the contact-point J. This takes place at each station.

Referring again to the circuit through the magnet A which originally caused the movement of the contact-maker P, if the receiver is off of the hook H then the circuit which passed through the magnet A would go from A to 47 by way of 80, M, 46, 47. The pin M is carried upon and insulated from the switchframe M, but is connected by a Wire to the contact 47. When the contact-maker P has been moved forward one step, the connection between 80 and M is broken, so that the contact-maker P cannot be moved forward an-' other step, as the circuit through the operating-magnet A is broken in alldirections. By this means a subscriber who attempts to listen into conversations between two other stations simply has his electrical connection moved to a blank contact-point, in which position he is not in connection with any station. It will be observed in the circuit by which the central office calls up the local station that the electrical impulse to the ringer passes through the contact-maker'P, and consequently no station will be rung up unless the said contactmaker is on either the contact-point J or J. Likewise when the subscriber at a local station rings up central the current has to pass through the'contact-maker P. Consequently if two subscribers are talking a subscriber at some other station cannot by operating his generator send an impulse over the line 50 to the central office until after the operator has returned all of the contact-makers to their normal positions.

What I claim is- 1. The combination with a central oflice, a wire extending therefrom, and a series of tele-. phone-stations connected to said wire, of a switching mechanism located at each station, magnets for operating and releasing said mechanism, a magneto-generator, two relayrnagnets connect-ed to said generator and oppositely polarized by the magnets of said generator, and means for sending an electrical current in either direction over said wire and through the two relay-magnets.

2. The combination with a switching mechanism, relay-magnets for controlling its operations, and a wire connecting said magnets in series, of a central station also connected to said wire, means for sending electrical impulses from said central station through said relay-magnets,a magneto-generator arranged to oppositely polarize said magnets, and a branch connection from said generator to said wire whereby said generator may send an electrical current to said central station but not through said magnets.

N. EMEL NORSTBOM.

Witnesses:

W. M. ROBERTS, O. L. REDFIELD. 

